1. Field of the Invention
The invention relates to a method and a device for processing image data, in particular, a method and a device for printing a plurality of copies of data expediently.
2. Description of Related Art
A printer does not receive image data from a computer each time the printing of a copy is completed when printing a plurality of copies. The printer stores the image data it received in the first printing in a storage device and prints the second copy and the rest of the copies based on the image data stored in the storage device.
In printing a plurality of copies, there are two ways of formats for the image data stored in the storage device of the printer; the BM compressed format and the printer language format.
The BM compressed format is a format, where the printer language data, or the image data consisting of a printer language transmitted from the computer is developed into a bitmap data and the BM compressed data, or the data obtained by compressing the bitmap data is stored in the storage device. The BM compressed data needs to be extended in order for the image data to be printed.
The printer language format is a format, where the printer language data transmitted from the computer is directly stored in the storage device. The printer language data needs to be developed into a bitmap data in order for the image data to be printed.
The volume of the printer language data is normally smaller than the volume of the BM compressed data. From the standpoint of effectively using the storage device for storing the image data, it is advantageous to store it as a printer language data.
Various printers with the above consideration have been proposed recently. For example, a Publication of Unexamined Japanese Patent Application, JP-A-9-193486 discloses a printer, where an image data is stored as a printer language data in a storage device of the printer such as a hard disk device if the available capacity of the storage device is small, and the image data is stored as a BM compressed data if the available capacity of the storage device is sufficient.
However, such a printer is not always advantageous for the following two reasons:
First, a printer language data obtained by converting an image having graphics with PostScript may have a larger volume of data than a comparable BM compressed data. Therefore, storing an image data as a printer language data may not necessarily be an effective usage of the printer's storage device.
Secondly, an image data stored as a printer language data in the storage device may take too long to print. More specifically, the time required to develop a printer language data corresponding to one page of document into a bitmap data exceeds the time required to print a page of document, the time required for the printing process may become undesirably long.
The printing time, as mentioned here, is defined as the time span between the time point when the system begins to write a bitmap data corresponding to the current page of the document on a photoconductor of an electronic photography printer and the time point when it becomes possible to write the bitmap data of the next page. For example, a printer that is capable of printing 60 pages per minute, the printing time is one second.
On the other hand, in order to avoid the printing process time from elongating, it is desirable to store the image data in a storage device as a bitmap data, which does not require a developing time. However, uniformly storing all image data as bitmap data requires a storage device with a large capacity. It creates a problem for the effective usage of the storage device.
Consequently, the printers proposed in the past, such as a printer that uniformly stores all image data as printer language data due to the limited space available in the storage device such as a hard disk device used for storing image data, and a printer that uniformly stores all image data as BM compressed data do not have sufficient capabilities from the standpoint of the effective use of the storage devices and the shortening of the printing process.
Another types of printer that have the reprinting capability are also known. The reprinting function is a capability of a printer to print one copy of an image data as instructed by a computer and then print extra copies of the same image data without further instructions from the computer. More specifically, the reprinting capability enables the printer to execute the next printing based on the image data stored in the storage device during the first printing.
However, the printers equipped with the reprinting capability lack due considerations for the format of storing image data in the storage device as well. Thus, they do not have sufficient capabilities.
Another type of printers also known to the public are network printers that are capable of consigning printing jobs to different printers connected to the same networks. If printing of a plurality of copies is specified, a network printer can delegate the job of printing some of the copies to a different printer, or delegate to a different printer the rest of the work if printing cannot be continued due to a malfunction. The delegation of the printing jobs requires the transfer of the image data stored in the storage device of the network printer to the different printer.
However, these causes a problem associated with the data transfer time in addition to the aforementioned problems associated with the effective usage of the storage device and the printing process time. For example, if the volume of the printer language data is greater than the volume of the BM compressed data, the time required for transferring the image data consisting of the printer language data becomes large, and the network load increases. On the other hand, if all image data are uniformly stored as the BM compressed data, the volume of the BM compressed data usually becomes larger than the volume of the printer language data. In addition, the time required for transferring the image data consisting of the BM compressed data to a different printer becomes large.